In most land-based drilling operations, such as when drilling for oil and gas on land, it is necessary to transport a drilling rig to the site where the drilling operations will take place. Typically, these drilling rigs are very large and, thus, must be transported to the drilling site in several pieces. These rigs are typically transported in pieces that comprise the three main sections of a drilling rig: the substructure, the equipment floor (or drill floor), and the mast. Depending on the size of the drilling rig, the substructure, the equipment floor, and the mast may each be further broken down into multiple pieces for ease of transportation.
The drill floor of the drilling rig is comprised of several segments, all of which, when assembled together, provide the platform or the “floor” for the drilling equipment and the mast that will be used in the drilling operations. It has become the custom to use a drill floor that is elevated above ground level in order to provide clearance for relatively tall blow-out prevention apparatus and other well head equipment used in drilling oil and gas wells. One embodiment of such an elevated-floor drilling rig structure is disclosed in U.S. Pat. No. 4,831,795 to Sorokan.
If an elevated drill floor is used, the drill floor is often connected to a collapsible elevating frame that, when assembled, can be raised—thereby raising the drill floor above the ground. The collapsible elevating frame is part of the substructure and is typically connected to “base side boxes” that form the base upon which the drilling rig stands and to “drill floor side boxes” that form a part of the drill floor.
Once the pieces of the drilling rig reach the site, the complete drilling rig must be reassembled so that drilling operations can commence. Assembling the drilling rig components on site, however, has proven to be a relatively complex and time-consuming process. In many of the prior art drilling rig structures, the drill floor, the substructure, and the mast must be constructed and connected together in, essentially, a piece-by-piece operation.
Additionally, after assembling the various pieces of the drill floor and the substructure, these large and extremely heavy sections of the drilling rig must be moved into position and aligned for connection. Specifically, to connect the drill floor to the substructure requires the rig personnel to align pin holes in the sides of the drill floor with pin holes in the sides of the substructure. Once aligned properly, the drill floor and the substructure must be “pinned” together. Aligning the pin holes of these large sections of drilling rig is a difficult and time consuming process that typically requires the use of a crane. This process can be extremely difficult if the area upon which the base side boxes rest is not well prepared such that it provides a fairly uniform and level “pad” for the drilling rig to rest on.
Further, to pin these sections together, it is necessary for one person to hold the pin in place while another person drives the pin through the pin holes with a sledge hammer or other device. This process is repeated until all the pins connecting the equipment floor and the substructure are driven in place. Given the fact that the equipment floor and the substructure typically require in excess of twenty (20) pins to connect them together, the process of aligning the pin holes and pinning these components together takes a significant amount of time. Moreover, the process of pinning these components together can be dangerous for the rig personnel performing such task.
Once the substructure of the drilling rig—consisting of the side boxes, the elevating frames, and the drill floor—is assembled and positioned over the well center, there is still a substantial amount of work that must be done to completely assemble the drilling rig. For example, the mast of the rig must be completely assembled, connected in place on the drill floor, and raised to the operational position prior to the drill floor being elevated. As with the substructure, assembling a mast at the drill site and positioning it for connection to the drill floor is a difficult and time consuming task—especially in light of the fact that the drilling rig mast is typically in the range of 100 to 180 feet tall depending on the size of the rig.
Once assembled, the mast must be raised to the operational position. In many prior art drilling rigs, the mast is raised by the drawworks. Use of the drawworks to raise the mast, however, requires that the drawworks is operational. The process of getting the drawworks operational is a complex and time-consuming process that can further delay the assembly of the drilling rig.
After the mast is raised, the entire drill floor must be raised to its elevated position—via the collapsible elevating frames of the substructure—and locked in place. Raising the equipment floor often requires the use of gin pole assemblies. These gin pole assemblies add additional weight to the substructure that must be transported from location to location. The gin pole assemblies also must be assembled and erected before elevating the drill floor. After the rig floor is raised, the gin pole assemblies must be “pinned” to the rig floor to secure the floor in the elevated position. As such, the gin poles must be pinned at the height of the elevated drill floor—a height that is often twenty-five feet or more. Pinning the gin poles to the elevated rig floor is thus time consuming and potentially dangerous to rig personnel.
As indicated from the above discussion, the assembly of prior art drilling rigs is a complex, labor-intensive process that takes a substantial amount of time. In today's oil industry, oil companies are becoming increasingly more reluctant to pay for this “rig up” time. Additionally, oil companies are becoming increasingly more reluctant to pay for the time it takes to transport a drilling rig from one location to another. Thus, it is becoming more and more critical for the operators of drilling rigs to minimize the “down time” associated with transporting and assembling drilling rigs so that the return on the substantial capital expenditure associated with building these rigs can be maximized.
Accordingly, what is needed is a drilling rig that can be transported from location to location and assembled at the drilling site more efficiently than the prior art drilling rigs. It is an object of the present invention to provide a method and apparatus for transporting a drilling rig to a drilling site and assembling it on site in significantly less time than prior art drilling rigs. Those and other objectives will become apparent to those of skill in the art from a review of the specification below.